Liu Zheng, Yang Jin-Gui, Ma Li-Hui, Ke Zeng-Ming, Hu Yu-Mei, Yan Xiao-Ying
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China.
Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2021 Jan;32(1):113-122. doi: 10.13287/j.1001-9332.202101.017.
Net primary productivity (NPP) of grassland is a key link and important part of the ecosystem's carbon cycle. We estimated the changes of NPP in grasslands of the Loess Plateau with unchanged land use types during 2000-2015 and analyzed its responses to the variation of main climate factors (annual precipitation, annual heavy rainfall, annual effective rainfall days, annual average temperature, annual maximum temperature, annual minimum temperature) using piecewise linear regression and Pearson correlation analysis. The driving factors of grassland NPP were further analyzed by pixel-by-pixel with boosted regression tree analysis. The results showed that annual mean grassland NPP in the Loess Plateau showed an increasing trend during the study period, with 51.3% of the total grassland area showing a significant increasing trend. The average increase rate of annual mean NPP declined from 15.23 g C·m·a in 2000-2004 to 3.58 g C·m·a in 2004-2015. There was a significant positive correlation between grassland NPP and precipitation, but negative correlation with temperature factors. Annual precipitation was the dominant climatic factor affecting NPP of the whole study area with the highest relative importance. Annual maximum temperature was the dominant driving force of grassland NPP of central Loess Plateau, while annual minimum temperature mainly affected the growth of grassland in high-altitude area of the western Loess Plateau.
草地净初级生产力（NPP）是生态系统碳循环的关键环节和重要组成部分。我们估算了2000 - 2015年黄土高原土地利用类型未发生变化的草地NPP变化情况，并采用分段线性回归和Pearson相关分析方法，分析了其对主要气候因子（年降水量、年暴雨量、年有效降雨日数、年平均气温、年最高气温、年最低气温）变化的响应。利用增强回归树分析逐像元进一步分析了草地NPP的驱动因素。结果表明，研究期间黄土高原草地年平均NPP呈增加趋势，其中51.3%的草地面积呈显著增加趋势。年平均NPP的平均增加速率从2000 - 2004年的15.23 g C·m⁻²·a下降至2004 - 2015年的3.58 g C·m⁻²·a。草地NPP与降水量呈显著正相关，与温度因子呈负相关。年降水量是影响整个研究区域NPP的主导气候因子，相对重要性最高。年最高气温是黄土高原中部草地NPP的主导驱动力，而年最低气温主要影响黄土高原西部高海拔地区草地的生长。
